Time controlled or electric clock thermostats have for many years required at least three wires to connect the thermostat to a remote source of power and a control apparatus for a system for controlling the supply of temperature condition medium to the space wherein the thermostat is located. In the modification of original construction in which two wires are required for a simple thermostat, considerable difficulty is experienced when the system is to be converted for use with a clock thermostat as extra wires are pulled through the wall.
To overcome the necessity of pulling extra wires to power a clock thermostat over the same two wires on which the control apparatus is controlled, various expensive schemes have been provided such as in the Clifford L. Nelson et al U.S. Pat. No. 3,620,448, issued Nov. 16, 1971, and the Balthasar H. Pinckaers U.S. Pat. No. 3,599,863, issued Aug. 17, 1971, wherein the clock motor is powered over the two wires and a signal of a different power factor or waveform is superimposed over the two wires for controlling the remote control apparatus.
Obviously, with the advent of lower power, extremely accurate battery driven time controlled units or clocks, such as the crystal oscillator type now available, the use of such a motor for powering an electric clock thermostat has been proposed, however, because of the torque requirement that the motor must have to do the added work of directly moving a mechanism which changes the temperature maintained in the space, power required from such a battery is large enough that that frequency changing or recharging of the battery must be accomplished.
The present invention provides a rechargeable battery powered electric clock thermostat for use in a system for controlling remote control apparatus over two wires and for connecting the battery through a charging circuit over the same two wires to a remote power source; so that, an electric clock thermostat can be used to replace a simple thermostat without the expense of additional wires for providing a control circuit for the thermostat and an energization circuit for the clock motor.